Myology Flashcards
(101 cards)
1
Q
3 Types of Muscle Tissue
A
- Skeletal
- Smooth
- Cardiac
2
Q
4 Characteristics of Muscle Tissue
A
- Electrical Excitability
- Contractility
- Extensibility
- Elasticity
3
Q
The ability to respond to certain stimuli by producing electrical signals.
A
Electrical Excitability
4
Q
The ability of the muscle tissue to generate tension (force) when stimulated by an AP.
A
Contractility
5
Q
The ability of the muscle to stretch (lengthen) without being damaged
A
Extensibility
6
Q
The ability of the muscle tissue to return to its original shape after contraction or stretch
A
Elasticity
7
Q
A.k.a for Skeletal Muscle
A
Striated Muscle
8
Q
Do skeletal muscles have voluntary or involuntary control?
A
Voluntary/conscious (also subject to involuntary)
9
Q
Describe striations
A
Alternating light and dark bands that are characteristic to Skeletal muscle
10
Q
Hierarchy Of Skeletal Muscle Organization
A
- Muscle
- Fascicle
- Muscle Fibre (Muscle Cell)
- Myofibril
11
Q
3 Points of Muscles
A
- size: cm
- Named
- Subdivided into bundles of fascicles
12
Q
2 Points of Fascicles
A
- size: mm
2. Each fascicle made of many muscle fibres
13
Q
Muscle Fibre A.k.a
A
Muscle Cell
14
Q
Shape of Muscle Fibres
A
Cylindrical
15
Q
The cell (plasma) membrane of the muscle cell
A
Sarcolemma
16
Q
Tiny invaginations tunnel in from the sarcolemma towards the centre of the muscle cell
A
Transverse Tubules (T-tubules)
17
Q
The cytoplasm of the muscle fibres–lots of glycogen
A
Sarcoplasm
18
Q
A protein that binds oxygen that has diffused into the muscle cell and delivers it to the mitochondria
A
Myoglobin
19
Q
3 Additional Points to Muscle Fibres.
A
- Lots of mitochondria
- Multinucleated
- Filled with myofibrils
20
Q
Specialized contractile organelles of the muscle cell.
A
Myofibrils
21
Q
4 Points of Myofibrils
A
- The extend the length of the muscle fibre
- Held in place by cytoskeletal proteins
- Sarcoplasmic Reticulum
- Contain a number of sarcomeres arranged in series
22
Q
Fluid filled tubes and sacs running along and surrounding each myofibril. (1 more point.)
A
Sarcoplasmic Reticulum
-They store and release calcium into the cell when needed
23
Q
Functional unit of a myofibril
A
The Sarcomere
24
Q
What are sarcomere’s two contractile proteins? What do they do?
A
- Actin: make up the thin filaments
2. Myosin: make up the thick filaments
25
What generates force/contraction?
Thick and thin filaments made by Myosin and Actin interacting by overlapping
26
What gives skeletal muscle its striated appearance?
Thick/thin filaments overlap creates light and dark strips
27
What must happen for a skeletal muscle to generate tension
The muscle must be stimulated by a nerve signal from a motor neuron.
28
A nerve cell that stimulates muscles to contract.
Motor Neuron
29
What is the neuromuscular junction and how is it formed?
- Axon connects with muscle--branches into axon terminals
| - Each axon terminal forms junction with the sarcolemma of multiple different muscle fibres
30
What is between the axon terminal and the sarcolemma? What happens as a result?
Gap between is the synaptic cleft
| As a result axon terminal and sarcolemma never touch
31
Explain the process for a skeletal muscle to generate tension.
Signal arrives, neurotransmitter is released, crosses synaptic cleft, stimulates sarcolemma, muscle continues signal
32
What happens when the signal reaches the muscle fibres?
1. Crosses synaptic cleft
2. Continues by the muscle fibres and spreads out across the sarcolemma
3. Travels down T-tubules and stimulates sarcoplasmic reticulum to release calcium
33
What does the calcium released by the sarcoplasmic reticulum do?
Allows myosin (thick filament) to connect with actin (thin filament)
34
What is ratcheting? What does it do?
-Myosin pulls and slides the actin filaments together, disengages and starts again
-Shortens the sarcomere, the myofibril, the muscle fibre, the muscle
USES ATP!
35
What happens to the ratcheting process when the APs stop?
The sarcoplasmic reticulum pumps calcium back inside. (ATP) Without sufficient calcium, thick filaments can't continue ratcheting of thin filaments.
Tension generation stops.
36
What is a motor unit?
The motor neuron and all the skeletal muscle fibres it innervates
(-1 motor neuron can innervate more than 1 mm fibre
-Each mm fibre can only be innervated by 1 motor neuron)
37
How much ATP is stored in muscle fibres?
Enough to last for ~ 3 seconds
38
3 Energy Pathways through which ATP can be generated
1. Creatine Phosphate
2. Anerobic Glycolysis
3. Aerobic Cellular Respiration
39
Creatine Phosphate A.k.a
Phosphocreatine, ATP-PCr, Anaerobic Alactic
40
What happens in a ATP-PCr Pathway?
Enzyme splits PCr, energy is released to form ATP
| -PCr molecule stores high amounts of energy in chemical bonds
41
How long does the Phosphocreatine Pathway provide energy. When is it used?
3-5 seconds of maximal contraction
Used as first source of energy when muscle contraction begins
42
Creatine Phosphate oxygen and lactic levels.
Anaerobic, Alactic
43
Anaerobic Glycolysis A.k.a
Anaerobic Lactic
44
If muscle activity continues, what happens when the initial PCr is depleted in the context of muscles?
Glucose is then used to make ATP (Anaerobic Glycolysis)
45
How long does the Anaerobic Glycolysis Pathway provide energy. When is it used?
Capable of supplying energy for 30-40 seconds
2nd Pathway used
46
What is a metabolic by-product of anaerobic glycolysis?
Lactic Acid/Lactate
47
At lower levels of activity, what happens to lactate?
```
Any lactate produced is consumed by:
-other muscle fibres
-active nearby muscles
-and heart
Does not accumulate!
```
48
What is the Cori cycle?
Lactate can also be converted back into glucose/glycogen in the liver
49
What is lactic acid's half life?
15-25mins
| Cleared in a matter of hours.
50
What happens in an Aerobic Cellular Respiration?
Oxygen is delivered, pyruvic acid enters the mitochondria , produce lots of ATP
51
Where does the oxygen in an aerobic cellular respiration come from?
Myoglobin or oxygen diffused from the bloodstream
52
When would your body use the Aerobic Cellular Respiration pathway?
When you are able to get oxygen into the cells. (At rest or low-moderate intensity exercises.) Activity longer than 10min.
53
What are the differences in skeletal muscle fibre types?
1. Speed at which they generate tension
2. How they use different energy substrates
3. How they fatigue
54
What are the 3 main types of Skeletal Muscle Cells?
1. Slow Oxidative
2. Fast Oxidative-Glycolytic
3. Fast Glycolytic
55
Slow Oxidative Fibres A.k.a
Type 1, slow-twitch fibres
56
When are Slow Oxidative Fibres recruited and what is their resistance to fatigue?
1st
| Fatigue Resistant
57
When is Slow Oxidative Fibres used and how does is generate ATP?
Endurance-type functions (maintaining posture, marathon)
| Aerobic Cellular Respiration
58
What 3 things must Slow Oxidative Fibres have?
LOTS OF...
1. Myoglobin
2. Mitochondria
3. Capillaries
59
With Slow-twitch fibres immobilization what happens to the muscles more so than other fibre types?
Atrophy faster
60
Fast Oxidative-Glycolytic A.k.a
Type IIa fibres
61
When are Fast Oxidative-Glycolytic recruited and what is their resistance to fatigue?
2nd
| Moderately high resistant to fatigue
62
When is Fast Oxidative-Glycolytic used and how does it generate ATP?
Used in endurance (walking), and shorter-duration functions (sprinting)
Aerobic and Anaerobic Pathways
63
What are Fast Oxidative-Glycolytic mitochondria, myoglobin, and capillary levels?
Intermediate amounts
64
Fast Glycolytic Fibres A.k.a
Type IIx fibres
65
When are Fast Glycolytic Fibres recruited and what is their resistance to fatigue?
3rd
| Low resistance to fatigue
66
When is Fast Glycolytic Fibres used and how does it generate ATP?
High intensity, short duration activities (weight lifting, slap shot) and shorter-duration functions (sprinting)
Anaerobic Pathways
67
What are Fast Glycolytic Fibres mitochondria, myoglobin, and capillary levels?
Relatively Low
68
What is true about the distribution of Muscle Fibres?
Most muscles are a mix of SO, FOG, FG fibres, within a motor unit, all fibre types are the same type
69
How do motor units contract?
From smallest/weakest to largest/strongest
70
To increase the amount of force generated...
1. increase the number of motor units recruited
| 2. Increase the frequency of neuronal AP firing
71
What is most effective for the forcefulness of contraction?
The length of the sarcomeres within a muscle before the contraction begins.
72
The greatest ability to generate tension is at..
resting length (optimal overlap)
73
Decreased ability to generate tension
- Lengthened (minimal overlap)
| - Shortened (excessive overlap)
74
Isotonic vs Isometric Contraction
Isotonic: mm contraction through a range against a resistance that is not changing
Isometric: mm contraction where there is no visible change to muscle
75
Concentric vs Eccentric Contraction
Concentric: shortening
Eccentric: lengthening
76
MM Contraction w/ Equipment: Variable Resistance vs Isokinetic
Variable Resistance: equip varies the resistance to match strength curve
Isokinetic: equip keeps the velocity of movement constant
77
What is Resting Tone?
Small amount of tension being generated in the muscle that is not strong enough to produce movement
78
What is Twitch Contraction?
Brief contraction of all muscle fibres in a motor unit in response to a single AP in its motor neuron
79
A lack of tone from the nerve being damaged or cut
Flaccidity
80
Increase muscle size
Hypertrophy
81
Decrease muscle size
Atrophy
82
The inability of a muscle to function at the required level
Fatigue
83
What are 4 common types/causes of fatigue
1. Energy Substrate Depletion (diabetes, fasting, sick)
2. Metabolic by-products (Exercising in heat)
3. Neurological Fatigue (AP for long time, physiological)
4. CNS Fatigue (Motivation, depression)
84
What are satellite cells?
-undifferentiated muscle cells
-actively involved in muscle repair and regeneration
(can become muscle cell, not as good, better than scar tissue)
-limited capacity
85
Surrounds entire muscle
Epimysium
86
Surrounds the fasicles
Perimysium
87
Surrounds muscle fibres
Endomysium
88
What is a tendon?
Interconnected epimysium, perimysium, and endomysium that extend beyond the muscle fibres to connect the muscle to the periosteum
89
Transition from muscle tissue to tendon
Musculotendinous Junction
90
Transition from tendon to periosteum
Tendoperiosteal Junction
91
Broad, flat tendon
Aponeurosis
92
Tube that surrounds a tendon for protection
Tendon Sheath
93
Cardiac muscles fibres branch, the ends fit tightly together with neighbouring fibres at junctions called..
Intercalated Discs
94
What junctions are involved and is the control voluntary/involuntary? (Cardiac)
Anchoring: Holds fibres together
Gap: Cells to communicate
Involuntary
95
Specialized cells within the heart can generate their own electrical signals (pacemaker)
Autorhythmicity
96
Where is smooth muscle found? How is it shaped?
Walls of hollow tubes
| Spindle-shaped
97
What junctions are involved and is the control voluntary/involuntary? (Smooth)
Gap junctions
| Involuntary
98
Where would you find single unit smooth muscle tissue
walls of small arteries, hollow organs
99
One AP supplies several smooth muscle fibres
Single Unit Smooth Muscle Tissue
| gap junctions function as single unit
100
Where would you find multiunit smooth muscle tissue
Walls of large arteries, airways in lungs, arrector pilli, muscles of iris
101
One motor neuron terminal supplies one smooth muscle fibre
Multiunit Smooth muscle
